This application claims the benefit under 35 U.S.C. § 119(a) of Korean Patent Application No. 2003-62177, filed on Sep. 5, 2003, in the Korean Intellectual Property Office, the disclosure of which is herein incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to a liquid electrophotographic image forming apparatus. More particularly, the present invention relates to a developing device for a liquid electrophotographic image forming apparatus, which removes substantially all of the ink remaining in an ink reservoir after a printing operation is performed, thereby lengthening the life span of the developing device.
2. Description of the Related Art
In general, liquid electrophotographic image forming devices form an electrostatic latent image which corresponds to a desired image by radiating light on a photosensitive body. The electrostatic latent image is developed with ink having a predetermined color, thereby obtaining a desired image.
FIG. 1 illustrates a conventional developing device for a liquid electrophotographic image forming apparatus. Referring to FIG. 1, the conventional developing device for a liquid electrophotographic image forming apparatus includes an ink cartridge 40 in which ink is stored, an ink reservoir 26 in which ink supplied from the ink cartridge 40 is accommodated, and a developing roller 12 which develops an electrostatic latent image formed on a photosensitive body 10 with ink supplied from the ink reservoir 26.
A deposit roller 16 which applies ink from the ink reservoir 26 to the surface of the developing roller 12, a metering roller 14 which regulates ink applied to the surface of the developing roller 12 to a predetermined thickness, and a cleaning roller 18 which cleans undeveloped ink from the surface of the developing roller 12 after development. The deposit roller 16, metering roller 14 and cleaning roller 18 are located around developing roller 12. A light scanning unit (LSU) 20 forms an electrostatic latent image by radiating light on the photosensitive body 10, and a cleaning blade 22 removes ink remaining on the surface of the photosensitive body 10. Also, a waste ink reservoir 24 holds waste ink removed by the cleaning blade 22.
In the above structure, if a first pump P1 is driven during the development operation, ink is supplied to the ink reservoir 26 from the ink cartridge 40 through a first through hole 30. Subsequently, ink is supplied by the deposit roller 16 to the developing roller 12, and the developing roller 12 is rotated while contacting the photosensitive body 10, thereby developing the electrostatic latent image formed on the photosensitive body 10. Ink leaking out of the ink reservoir 26 is collected in an ink container 28. Subsequently, ink flows through a second through hole 32 and is returned to the ink cartridge 40 for storage. To this end, a second pump P2 is located in the path connecting the ink cartridge 40 to the ink container 28.
Meanwhile, if a printing operation is completed, the first pump P1 is driven in the reverse direction and ink remaining in the ink reservoir 26 flows through the first through hole 30 and is returned to the ink cartridge 40.
FIGS. 2A and 2B respectively show an elevation view and a cross-sectional view illustrating a structure of the ink reservoir 26 of FIG. 1. Referring to FIGS. 2A and 2B, the first through hole 30 for supplying and removing ink is formed under the ink reservoir 26, and a bottom surface of the ink reservoir 26 is inclined toward the first through hole 30. Ink in the ink reservoir 26 moves to the first through hole 30 by gravity. However, high-concentration ink does not flow quickly by gravity alone. Even though high-concentration ink moves to the first through hole 30 by gravity, the amount of time required may be reduced by using a mechanical means to assist the movement of the ink to the first through hole 30.